SALT LAKE CITY — They can't remember the first one, they thought the ones when they were teenagers were lame, and they were absolutely sure they'd never still be having them.

But just try to get them to stop partying now.

For 40 years straight, four girls, now women, who started life out on the very same day, Jan. 25, 1973, in the very same place, LDS Hospital, have celebrated their birthdays together.

They're not quadruplets. They typically don't even see each other the rest of the year. But the day they were born, their mothers all shared the same hospital room — a routine thing back then — and the moms made a pact: Every year they would get their daughters back together to celebrate the blessed day.

And so they have. Each January, Kim, Shelley, Shawnee and Rebecca — the birthday girls — have helped each other ring in one more big one.

For 30 straight years, from 1974 through 2004, everyone attended — until Shelley's mom, Diane, died of cancer later that year and Kim's mom, Dorothy, died of a stroke in 2006. That thinned the ranks but only increased the enthusiasm.

Something the birthday girls did with their moms transformed into something they do for their moms.

"It's become a tribute to all of them," says Shelley Butterfield Cundick. "For all they've done for us and for always making it special."

It was Kim's mom's idea in the beginning. Dorothy Jolley came up with the brainstorm the morning of Jan. 26 as all four talked in their hospital room, flush with the thrill of delivery: Let's all get together when they turn 1. Diane Butterfield (Shelley's mom), LuGene New (Shawnee's mom) and Mary Flowers (Rebecca's mom) couldn't agree fast enough.

A year later, everyone showed up at Kim's place.

Every year thereafter the mom's took turns hosting the bash. When the girls turned 4, it was Mary Flowers' turn, and she had everybody over to Rebecca's home in Holladay.

Kim's mom had alerted the Deseret News in advance and a photographer arrived to take the girls' picture.

When the photo and a short write-up appeared in the newspaper, Kim's mom announced that they'd do it again when the girls turned 40.

"She always used to say that," recalls Kim, "and we used to think, right, we're going to do this till we're 40? That's so old!"

But be careful what you call old. Last week, at the Red Robin restaurant in West Valley City, there the birthday girls were, looking younger than ever, once again posing for the Deseret News.

Just one mother, Shawnee's, attended this time. Rebecca's mom is away on an LDS mission. Nonetheless, proper tribute was paid to every mom.

LuGene recalled fondly that day 40 years ago at the hospital. "We were all so ecstatic," she said. "We thought the idea (to meet every year) was wonderful."

The parties have evolved over the years. There were sledding and skating parties and outings at Chuck E. Cheese's when the girls were younger. Later, in their teenage years, the girls came a bit reluctantly.

"We talked about how lame it was," remembers Shelley.

"It was like, I have to give up my Saturday for that?" says Shawnee, "although it's not like it was ever horrible once we got there."

But with their moms' help, they survived being teenagers, and every other obstacle that has come up over the years since. As each girl married and started her own family, the party remained a steadfast absolute, with no husbands and children invited. Just the birthday girls and their mothers.

Rebecca remembers that as a kid, "everyone was jealous because I always got two parties," and that hasn't changed.

To this day the girls remain close friends, albeit once-a-year close friends. The rest of the year they stay in their own circles and lives.

"But when we get together we start back up like we never left," says Kim. "Once a year, we get to see how we've changed."

And more importantly, as they reunite with their moms, how they haven't.